Elastomeric bumper

ABSTRACT

An integral elongated bumper having impact absorption properties for mounting on a conventional basic metal bumper of an automobile comprising an overlay of elastomeric material covering a core of elastomeric material having short fibers dispersed densely and randomly throughout said core and integrally bonded to the core substance, increasing the impact resistance of said core over that of the overlay.

McKenzie ELASTOMERIC BUMPER [75] Inventor: Ross A. McKenzie, Toronto 3,On-

tario, Canada [73] Assignee: National Rubber Company Limited,

Toronto, Ontario, Canada [22] Filed: Oct. 14, 1971 [21] Appl. N0.:189,452

[52] U.S. Cl. ..293/71 R, 267/140 [51] Int. Cl ..B60r 19/08 [58] Fieldof Search ..293/1, DIG. 4, 62,

293/71 R,71 F; 52/716, 717, 718; 267/139, 140;152/3l1,312,354

[5 6] References Cited UNITED STATES PATENTS 1,704,768 3/1969 Sigman..293/71 R DuBetz et a1 ..l52/354 Moore ..293/l Primary Examiner-GeraldM. Forlenza Assistant ExaminerRobert Saifer Attorney-Leon Atthurs [57]ABSTRACT An integral elongated bumper having impact absorptionproperties for mounting on a conventional basic metal bumper of anautomobile comprising an overlay of elastomeric material covering a coreof elastomeric material having short fibers dispersed densely andrandomly throughout said core and integrally bonded to the coresubstance, increasing the impact resistance of said core over that ofthe overlay.

13 Claims, 5 Drawing Figures PATENTED MAY 2 2 I973 FIG 3 ELASTOMERICBUMPER This invention relates to improvement in elastomeric bumperswhich are frequently mounted on the conventional basic metal bumper ofan automobile and to the process of making them. Essentially, theelastomeric bumper with which the invention is concerned is forutilitarian purposes as distinguished from purely ornamental purposes.An example of utilitarian function within the scope of the invention isan elastomeric bumper attached to the basic bumper of a vehicle; anelastomer such as rubber being used as the component substance thereofbecause of its cushioning or shock absorbing properties. While virtuallyall the properties of rubber or its substitutes are variable within widelimits e.g., hardness, elasticity, color, grade and so forth, theinvention is principally concerned with rubber or an equivalentelastomer of commercial character.

Moreover, while the invention contemplates bumpers formed of elastomericmaterial some of said elastomer contains a dispersion of fibers. Todistinguish between them, the elastomer in which said fibers aredispersed will be hereinafter referred to as an elastomer composite orcore while that without the dispersion will be referred to as an overlayor veneer of elastomeric material which, in the present embodiment, isintegrally bonded to the core and carries the frontal configuration ofthe bumper.

An elastomeric bumper as contemplated by the present invention isfrequently mounted on the conventional basic metal bumper of anautomobile to cushion the impact which it receives in normal use and soprolong its useful life. Heretofore, such elastomeric bumpers tended todeteriorate rather rapidly according to the stresses to which they wereexposed.

The elastomeric bumpers aforesaid are mounted on the automobile by themeans of threaded studs which project rearwardly therefrom. In the past,having regard to the bumper substance heretofore used, it was necessaryto wire the studs together in order to retain them in the elastomeragainst the impact shocks sustained in use. Apart from the problems ofmanufacture occasioned by the inter-wired studs, the fact is that thewire itself was capable of deformation by the shocks aforesaid which, inturn, often warped or deformed the elastomeric bumper itself and henceproduced an unsightly result.

A principal object of the present invention, therefore, is to provide anelastomeric bumper having improved impact absorption properties coupledwith better wearing qualities, resistance to abrasion and a low thermalcoefficient of expansion.

A more specific object of the invention is to provide an elongatedbumper as aforesaid whose impact absorption and resistance propertiesare improved by a dense dispersion of fibers reinforcing the core of thebumper.

A further object of the present invention is to provide a bumper withits mounting studs discretely anchored and held in the core solelythrough the retentive properties of the core substance with itsreinforcing fibers embedded therein.

Further objects of the invention, more or less broad than the foregoingwill become apparent from the following description of the constituentparts, elements and principles of one embodiment of the invention givenherein solely by way of example with reference to the accompanyingdrawings wherein like reference numerals indicate like parts andwherein:

FIG. 1 is a perspective view of an elastomeric bumper according to theinvention which is mounted on a metal bumper of an automobile;

FIG. 2 is a cross-sectional view of the automobile bumper with theelastomeric bumper mounted thereon taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view of a hollow elastomeric bumper;

FIG. 4 is a perspective view of a portion of an elastomeric bumper withparts removed showing the bumper in greater detail, and

FIG. 5 is a cross-sectional view of a portion of the elastomeric bumpershown in FIG. 4 taken along the line 5-5 thereof.

In FIG. 1 is seen elastomeric bumper B mounted on a conventional metalbumper of a vehicle to cushion the impacts which it receives in normaluse.

As shown cross-sectionally in FIG. 2 the bumper B of the invention iscomprised of an elastomeric overlay 2 on a core 4 also formed ofelastomeric materials in which short fibers 6 are densely dispersed atrandom and integrally bonded to the core substance; it being observedthat the area of the core 4 as it appears in said FIG. 2 is greater thanthe corresponding area of the overlay.

To all intents and purposes the respective substances of the core 4 andoverlay 2 may be substantially the same. However, the dispersion offibers 6 in the core substance tends to increase its impact resistanceover that of overlay 2 but at the cost of some resilience and appearancein both of which respects the overlay 2 accordingly surpasses core 4.The overlay 2 also imparts improved weather resistance to bumper B; core4 being more susceptible to the elements, presumably, because of thefibers 6 embedded therein, for example.

The short fibers within the core are not only densely dispersed thereinbut, preferably, are also trained in the longitudinal direction of thecore 4, thus further adding to the tensile strength of the core. Priorto any curing procedures, the core substance with the fibers dispersedtherein is preliminarily calendered between a pair of conventionalcalendering rolls; the fibers in the calendered materials beingresultantly trained in a direction substantially perpendicular to theaxes of the calendering rolls. The said calendered materials with theirlongitudinally trained fibers are then formed into an elongated core 4with the fibers oriented in the longitudinal direction thereof.

Embedded within the core are spaced, preferably corrosion resistant,studs 8 projecting from the side 9 of the core not covered by theoverlay; each said stud 8 having a broad head 8' completely embedded inthe core substance as aforesaid with a shoulder 8", narrower than saidhead 8, lying approximately flush with the uncovered side 9 of the core4. A core 4 containing embedded fibers 6 as aforesaid has been found inpractice to possess great retentivity with regard to the studs 8 and toprovide rigid anchorage therefor. In the result, the interconnection ofthe studs as by a wire is rendered unnecessary whereby the studs may bedisposed discretely within the said core thereby simplifying themanufacturing procedure.

Moreover, the core 4 of the bumper B as hereinbefore described has beenfound to have a coefficient of thermal expansion lower than that of theoverlay. This is seen to provide a further advantage in that with thecore and overlay being integrally bonded together as will duly appear,the core will inhibit any tendency of the overlay to expand or contract,as the case may be, and thus enhance the dimensional stability of thebumer B.

p While the core 4 is preferably solid as shown in FIGS. 2 and 4, forexample, the invention need not, of course, be limited thereto as willbe apparent from FIG. 3 showing a hollow bumper in cross-section inwhich the inventive principles have been embodied.

In the process of making the bumper B, a core 4 is formed of anelastomer aforesaid having short fibers 6 dispersed densely and randomlythroughout it and integrally bonded to it. A thin overlay 2 ofelastomeric material which is completely or substantially free of fiberssuch as are embedded in core 4 is then integrally bonded to the latter.Once thus bonded and molded the overlay 2 carries the externalconfiguration of the bumper B.

Said core 4 in this embodiment is formed of an elastomer in which saidfibers 6 of nylon, rayon, fiberglass or the like are embedded asaforesaid while the elastomer is still uncured. Preferably, the fibersare on the order of one-fourth to 1 inch or so in length. This compositeof uncured elastomer and fibers is then passed through a calenderingprocess between a pair of conventional calendering rolls which tends toorient the fibers in the composite and train them in a directionsubstantially perpendicular to the axes of the calendering rolls. In thesubsequent forming of the core the calendered composite aforesaid isusually arranged so that the fibers 6 are trained in the longitudinaldirection of the core when it is finally molded as shown in FIG. 4. Aninteresting point to note at this juncture is that because of theaforesaid longitudinal orientation of the fibers, the core substance hasexhibited substantial resistance to tensile forces in view, presumably,of the tensile strength of the fibers themselves.

The calendered composite arranged as aforesaid with its fibers trainedin the longitudinal direction of the core to be formed is then moldedunder relatively low heat and high pressure producing an uncured orsemicured core with its fibers integrally bonded to the core substance.

Once the core is thus formed, the next step in the process involvesdepositing an overlay of uncured elastomeric material on said core witha bonding layer 10 sandwiched therebetween as shown in FIG. 4. The saidoverlay is subsequently molded to the core under relatively high heatand pressure vulcanizing both said overlay 2 and core 4 and integrallyuniting them into an integral mass whose external configuration iscarried by the overlay 2. It need hardly be observed at this point thatthe overlay 2 may embrace more or less of the core 4 than is shown inthe drawing; the final configuration thereof being dictated bycircumstances in specific cases.

As one preferred means of mounting the elastomeric bumper to the basicmetal bumper of an automobile, the threaded studs 8 shown in FIGS. 2 and5 are discretely embedded within the core during the molding thereof soas to project from the core side 9 not covered by the overlay; the studs8 being, of course, preferably pre-coated with an appropriate bondingmaterial.

What I claim is:

1. An integral elongated bumper having impact absorption propertiescomprising:

an overlay of elastomeric material;

a core of elastomeric material covered by said overlay and integraltherewith;

short fibers dispersed densely and randomly throughout said core andintegrally bonded to the core substance, increasing the impactresistance of said core over that of the overlay;

the cross-sectional area of said core exceeding that of the overlay.

2. A bumper as defined in claim 1 wherein said overlay provides asurface veneer for said core;

the overlay substance having greater resilience and weather resistancethan the core substance.

3. A bumper as defined in claim 1 wherein said fibers are trainedsubstantially in the longitudinal direction of the core.

4. A bumper as defined in claim 1 wherein said overlay covers one sideof said bumper and spaced studs, embedded in said core, project from itsother side; each said stud having a broad head embedded as aforesaid anda shoulder narrower than said head, which is approximately flush withthe said other bumper side.

5. A bumper as defined in claim 1 wherein said bumper is hollow.

6. A bumper as defined in claim 1 wherein said core has a lowercoefficient of thermal expansion than said overlay.

7. A bumper as defined in claim 2 wherein said fibers are trainedsubstantially in the longitudinal direction of the core providing saidcore with substantial tensile strength in its longitudinal direction.

8. A bumper as defined in claim 4 wherein said studs are discrete.

9. A bumper as defined in claim 4 wherein said studs are corrosionresistant.

10. A bumper as defined in claim 4 wherein said studs are corrosionresistant and discrete.

11. A bumper as defined in claim 7 wherein said overlay covers one sideof said bumper and spaced studs, embedded in said core, project from itsother side; each said stud having a broad head embedded as aforesaid anda shoulder narrower than said head, which is approximately flush withthe said other bumper side.

12. A bumper as defined in claim lll wherein said studs are discrete.

13. A bumper as defined in claim 11 wherein a bonding layer isinterposed between said overlay and said

2. A bumper as defined in claim 1 wherein said overlay provides asurface veneer for said core; the overlay substance having greaterresilience and weather resistance than the core substance.
 3. A bumperas defined in claim 1 wherein said fibers are trained substantially inthe longitudinal direction of the core.
 4. A bumper as defined in claim1 wherein said overlay covers one side of said bumper and spaced studs,embedded in said core, project from its other side; each said studhaving a broad head embedded as aforesaid and a shoulder narrower thansaid head, which is approximately flush with the said other bumper side.5. A bumper as defined in claim 1 wherein said bumper is hollow.
 6. Abumper as defined in claim 1 wherein said core has a lower coefficientof thermal expansion than said overlay.
 7. A bumper as defined in claim2 wherein said fibers are trained substantially in the longitudinaldirection of the core providing said core with substantial tensilestrength in its longitudinal direction.
 8. A bumper as defined in claim4 wherein said studs are discrete.
 9. A bumper as defined in claim 4wherein said studs are corrosion resistant.
 10. A bumper as defined inclaim 4 wherein said studs are corrosion resistant and discrete.
 11. Abumper as defined in claim 7 wherein said overlay covers one side ofsaid bumper and spaced studs, embedded in said core, project from itsother side; each said stud having a broad head embedded as aforesaid anda shoulder narrower than said head, which is approximately flush withthe said other bumper side.
 12. A bumper as defined in claim 11 whereinsaid studs are discrete.
 13. A bumper as defined in claim 11 wherein abonding layer is interposed between said overlay and said core.